This invention relates to a method for detecting an insufficient level of finish on yarn, more particularly, it relates to detecting such levels by monitoring the temperature of a stationary surface over which the yarn advances.
Substances known as finishes are usually applied to synthetic polymeric filaments for lubrication to reduce friction as they advance over guides, draw pins and other machine elements in various yarn handling processes. Finishes may also be applied to reduce the generation of static electricity, conduct such charges away, or provide soil or stain resistance capability to the yarn.
If the supply or application of finish is interrupted or greatly reduced, the yarn handling process may break down or the product will be unsatisfactory to the customer. Since finishes are usually colorless, the absence of finish even on the outside of a yarn package is difficult to detect, and a temporary interruption of finish within a yarn package is usually impossible to determine.
Methods of detecting the presence or absence of finish are known, employing instruments which respond to some characteristic of the finish such as conductance. However, such devices are often quite expensive and difficult to maintain, when each threadline of a multi-threadline machine must be inspected.